Okay Guwon (or whatever his name is) is not human, which is why he behaves this way. Of course it doesn't excuse his behavior but we understand why he acts like this. But the real question is why this obsession with creating a utopia if it is not human? Also, I don't think he's a "red flag", a "black flag" or whatever the flag , but more of a complex being who has trouble with human emotions and values. With the help of teach I think he will learn what he is trying to It means being human.
So yeah it's incest. "Yeah but they're not really related!" Yes, it's true but they call each other "Dad" and "son" so, we can see the family context between them. Even if they're not really related, the dad and the mom are married. So in front of the law and the society they're dad and son. In conclusion it's incest and it's disgusting. But I'm too curious to stop now 😞